1. Field of the Invention
The present invention relates to a material of a solar cell. More particularly, the present invention relates to an organic dye of a dye-sensitized solar cell (DSSC) and a DSSC using the same.
2. Description of Related Art
The increasing demand for power supply as well as environmental concern for the consumption of fossil fuel have triggered global research on the development of clean and renewable energy sources. Among possible alternates for fossil fuel energy, solar energy appears to be very attractive: covering 0.16% of the land of the Earth with 10% efficient solar conversion systems would provide power nearly twice the world's consumption rate of fossil energy. Though silicon- and other semiconductor-based solar cells (known as photovoltaic cells) have dominated the solar cell market for decades, DSSCs have also attracted considerable interest ever since the breakthrough made by Grätzel and co-workers (O'Regan, B.; Grätzel, M. Nature 1991, 353, 737). Efficiency record of about 11% has been achieved with ruthenium-based sensitizers developed by Grätzel and other groups. Though being developed later than ruthenium dyes, metal-free sensitizers also attract much attention and a high efficiency of about 9% has also been achieved for DSSCs based on a metal-free sensitizer.
Various metal-free dyes have been used for the construction of DSSCs. The inventors have reported metal-free sensitizers which consisted of an arylamine as the electron donor, a 2-cyanoacrylic acid as the electron acceptor, and a conjugated bridge containing thiophene moieties. Compared with benzenoid moieties, the thiophene can provide more effective conjugation and lower the energy of the charge transfer transition because of its smaller resonance energy (thiophene, 29 kcal mol−1; benzene, 36 kcal mol−1).